Jeremy Bentham was born in Houndsditch, London on 15 February 1748. He was the eldest son of Alicia Whitehorn, née Grove, who on 3 October 1745 had entered into he second marriage with Jeremiah Bentham, a successful practitioner in the Court of Chancery. (…) Six further children were born, of whom only the youngest, Samuel, born in 1757, survived beyond infancy. Death was never far away and on 6 January 1759, when Jeremy was ten years old, he lost his mother. (…) by 1755 he was considered robust enough to go to Westminster School.
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Recognizing that his eldest child was a prodigy, Jeremiah sent him at the tender age of 12, to the Queen's College, Oxford, where he took up residence in October 1760. (…) his graduation with a Bachelor of Arts degree in 1764 (he was reputedly the youngest person up to that time ever to graduate) proved extremely problematic. Graduation was conditional upon the graduand swearing to the statements of faith and discipline contained in the Thirty-nine Articles of the Church of England.
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Bentham could not bring himself to accept them. He realized, however, that not to swear, and thereby to disqualify himself from receiving his degree, would destroy his relationship with his father, who expected him to pursue a brilliant legal career, and even rise to the office of Lord Chancellor at the pinnacle of the profession. (…) On the other hand, to swear to the articles was an act of intellectual dishonesty. In the event, he swore, but it was a decision he always regretted, as he made clear over 50 years later: "by the view I found myself forced to take of the whole business, such an impression was made, as will never depart from me but with life." What is remarkable about this episode is that Bentham was a mere 16 years old at the time. His scepticism in relation to religious belief already ran deep, though the precise nature of that scepticism not easy to discern.
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The year 1769 – "a most interesting year" as Bentham himself called it – was important for a different reason. It was in 1769 that Bentham found a purpose for his life. All the pieces of the jigsaw suddenly came into place. His later reflections on this period of his life reveal an exposure to a very different literature from the one he had been allowed to peruse as a child. Prominent now were names such as Montesquieu, Helvétius, Beccaria and Voltaire – figures associated with the continental Enlightenment – and David Hume, David Hartley and Joseph Priestley – figures who were advancing radical philosophical and political views. Bentham brought together various elements from these thinkers to construct his version of the principle of UTILITY.
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In the late 1770s and early 1780s Bentham spent much of his time developing his notion of the science of legislation, founded upon the principle of utility. As noted above, one result of this endeavour was An Introduction to the Principles of Morals and Legislation. Here he argued that the right and proper end of government was the happiness of the community (…) and went on to develop his theory of punishment and produce a detailed classification of offences. In relation to punishment, he found inspiration in the work of Cesare Beccaria, who had stressed the importance of deterrence, proportionality and certainty of infliction. Bentham took Beccaria's ideas, related them systematically to the principle of UTILITY, and added elements of his own. He argued that the legislator, when assigning punishment to actions, had to take to account of the "profit" which accrued to the criminal, and the "mischief" which resulted to the community, from the commission of the offence.
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as he worked on the text which became An Introduction to the Principles of Morals and Legislation, Bentham became aware that in order to produce a code of laws, he needed to understand what a single (or individuated) law consisted in. but he also realizes that neither he, nor any one who had written before him, had properly defined what was meant by the notion of law – just what was this entity which was termed a law? Bentham embarked on an investigation which produced the text hitherto known as Of Laws in General in which he argued, with an incredible insight of sophistication, that a law was an expression of will on the part of a sovereign, who in turn was the person or body of persons, or some combination of persons and bodies, to whom the community was in a habit of obedience. Around the same time, he came to the conclusion that the most effective means of promoting the happiness of the community would be through the introduction of a complete code of laws, or a "pannomion" as he termed it. Such a code would be "all-comprehensive" and "rationalized". This meant that the code would be logically complete, in that all the terms used in the code would be clearly defined and that each single provision would be immediately followed by the reason which justified it, such justification bearing reference of course to the principle of UTILITY. (See the book: Bentham: A guide for the Perplexed, author: Philip Schofield, Professor of History of Legal and Political Thought, University College London, Director of the Bentham Project, Associate Editor of Utilitas.,)

Philosophers who share this vision of the proper function of social institutions like law and morality may differ on more than the best methods to attain it, as Aristotle noted, there is widespread agreement that happiness is the goal, but considerable disagreement as to what constitutes happiness. For Bentham the answer is simple: happiness is just pleasure and absence of pain. The value (or disvalue) of a pleasure (or pain) depends only on its intensity and duration, and can (at least in principle) be quantified precisely. Given this, we can reconstruct one line of Bentham's argument for the principle of UTILITY as something like the following:

The good of a society is the sum of happiness of the individuals in that society.

The purpose of morality is promotion of the good of society.

A moral principle is ideal if and only if universal conformity to it would maximize the good of society.

Universal conformity to the principle of UTILITY ("Act always so as to maximize total net balance of pleasures and pains") would maximize the good of society.

(See the book: The Classical Utilitarians: Bentham and Mill, author: John Troyer, Professor of Philosophy at the University of Connecticut)

Abstracts of Bentham's Principles of Morals and Legislation:

Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do. On the one hand the standard of right and wrong, on the other the chain of causes and effects, are fastened to their throne. They govern us in all we do, in all we say, in all we think: every effort we can make to throw off our subjection, will serve but to demonstrate and confirm it. In words a man may pretend to abjure their empire: but in reality he will remain subject to it all the while. The principle of utility recognises this subjection, and assumes it for the foundation of that system, the object of which is to rear the fabric of felicity by the hands of reason and of law. System which attempt to question it, deal in sounds instead of sense, in caprice instead of reason, in darkness instead of light. (Bentham: Principles of Morals and Legislation, c. I)

CHAPTER IV

Value of a Lot of Pleasure or Pain, How to be Measured

I. Use of this chapter. Pleasure then, and the avoidance of pains, are the ends which the legislator has in view: it behoves him therefore to understand their value. Pleasures and pains are the instruments he has to work with: it behoves him therefore to understand their force, which is again in other words their value.

II. Circumstances to be taken into the account in estimating the value of a pleasure or pain considered with reference to a single person, and by itself. To a person considered by himself, the value of a pleasure or pain considered by itself, will be greater or less, according to the four following circumstances:

Its intensity.

Its duration.

Its certainty or uncertainty.

Its propinquity or remoteness.

III. – considered as connected with other pleasures or pains. These are the circumstances which are to be considered in estimating a pleasure or a pain considered each of them by itself. But when the value of any pleasure or pain is considered for the purpose of estimating the tendency of any act by which it is produced, there are two other circumstances to be taken into account, these are,

Its fecundity, or the chance it has of being followed by sensations of the same kind: that is, pleasures, if it be a pleasure: pains, if it be a pain.

Its purity, or the chance it has of not being followed by sensations of opposite kind: that is: pains, if it be a pleasure, pleasures, if it be a pain

These two last, however, are in strictness and scarcely to be deemed properties of the pleasure or the pain itself; they are not, therefore, in strictness to be taken into the account of the value of that pleasure or that pain. They are in strictness to be deemed in properties only of the act, or other event, by which such pleasure or pain has been produced; and accordingly are only to be taken into the account of the tendency of such act or such event.

IV. – considered with reference to a number of persons. To a number of persons, with reference to each of whom the value of a pleasure or a pain is considered, it will be greater or less, according to seven circumstances: to wit, the six preceding ones; viz.

Its intensity.

Its duration.

Its certainty or uncertainty.

Its propinquity or remoteness.

Its fecundity.

Its purity.

And one other to wit:

Its extent; that is, the number of persons to whom it extends; or (in other words) who are affected by it.

V. Process for estimating the tendency of any act or event. To take an exact account then the general tendency of any act, by which the interests of a community are affected, proceeds as follows. Begin with any one person of those whose interests seem most immediately to be affected by it: and take an account,

Of the value of each distinguishable pleasure which appears to be produced by it in the first instance.

Of the value of each pain which appears to be produced by it in the first instance.

Of the value of each pleasure which appears to be produced by it after the first. This constitutes the fecundity of the first pleasure and the impurity of the first pain.

Of the value of each pain which appears to be produced by it after the first. This constitutes the fecundity of the first pain, and the impurity of the first pleasure.

Sum up all the values of all the pleasures on the one side, and those of all the pains on the other. The balance, if it be on the side of pleasure, will give the good tendency of act upon the whole, with respect to the interests of that individual person; if on the side of pain, the bad tendency of it upon the whole.

Take an account of the number of persons whose interests appear to be concerned; and repeat the above process with respect to each. Sum up the numbers expressive of the degrees of good tendency, which the act has, with respect to each individual, in regard to whom the tendency of it is good upon the whole: do this again with respect to each individual, in regard to whom the tendency of it is good upon the whole: do this again with respect to each individual, in regard to whom the tendency of it is bad upon the whole. Take the balance; which, if on the side of pleasure, will give the general good tendency of the act, with respect to the total number or community of individuals concerned; if on the side of pain, the general evil tendency, with respect to the same community.

VI. Use the foregoing process. It is not to be expected that this process should be strictly pursued previously to every moral judgement, or to every legislative of judicial operation. It may, however, be always kept in view: and as near as the process actually pursued on these occasions approaches to it, so near will such process approach to the character of an exact one.

VII. The same process applicable to good and evil, profit and mischief, and all other modifications of pleasure and pain. The same process is alike applicable to pleasure and pain, in whatever shape they appear: and by whatever denomination they are distinguished: to pleasure, whether it be called good (which is properly the cause or instrument of pleasure) or profit (which is distant pleasure, or the cause or instrument of distant pleasure), or convenience, benefit, emolument, happiness and so forth: to pain, whether it be called evil, (which corresponds to good) or mischief, or inconvenience , or disadvantage, or loss, or unhappiness, and so forth.

VIII. Conformity of men's practice to this theory. Nor is this a novel and unwarranted, any more than it is a useless theory. In all this there is nothing but what the practice of mankind, whosesoever they have a clear view of their own interest, is perfectly conformable too. An article of property an estate in land, for instance, is valuable, on what account? On account of the pleasures of all kinds which it enables a man to produce, and what comes to the same thing the pains of all kinds which it enables him to avert. But the value of such an article of property is universally understood to rise or fall according to the length or shortness of the time which a man has in it: the certainty or uncertainty of its coming into possession: and the nearness or remoteness of the time a which, if at all, it is to come into possession. As to the intensity of the pleasure which a man may derive from it, this is never thought of, because it depends upon the use which each particular person may come to make of it; which cannot be estimated till the particular pleasures he may come to derive from it, or the particular pains he may come to exclude by means of it, are brought to view. For the same reason, neither does he think of the fecundity or purity of those pleasures.

Thus much for pleasure and pain, happiness and unhappiness, in general.

Bibliography

“Offenses against One’s Self: Pederasty” An Essay on Pederasty (1785)

"Short Review of the Declaration" (1776). An attack on America's Declaration of Independence.

Fragment on Government (1776). This was an unsparing criticism of some introductory passages relating to political theory in William Blackstone's Commentaries on the Laws of England. The book, published anonymously, was well-received and credited to some of the greatest minds of the time. Bentham disagreed with Blackstone's defence of judge-made law, his defence of legal fictions, his theological formulation of the doctrine of mixed government, his appeal to a social contract and his use of the vocabulary of natural law. Bentham's "Fragment" was only a small part of a "Commentary on the Commentaries", which remained unpublished until the twentieth century.

Introduction to Principles of Morals and Legislation (printed for publication 1780, published 1789).

Defence of Usury (1787). Jeremy Bentham wrote a series of thirteen “Letters” addressed to Adam Smith, published in 1787 as Defence of Usury. Bentham’s main argument against the restriction is that “projectors” generate positive externalities. Gilbert K. Chesterton identified Bentham's essay on usury as the very beginning of the 'modern world.' Bentham’s arguments were very influential. “Writers of eminence” moved to abolish the restriction, and repeal was achieved in stages and fully achieved in England in 1854. There is little evidence as to Smith’s reaction. He did not revise the offending passages in The Wealth of Nations, but Smith made little or no substantial revisions after the third edition of 1784.